A New Fluorescent Test for Cell Vitality Using Calcofluor White M2R

The fluorescent fabric-brightener dye, Calcofluor white M2R (CFW), can be used to distinguish between living and dead cells from a variety of animal and plant sources. CFW does not stain living mouse fibroblasts or trout red blood cells and stains only the cell walls in living cells from the epidermis of onion bulb scale, staminal hairs of Tradescantia, and longitudinal sections of broad bean stems and roots. Heat-killed plant or animal cells are recognized by their lightly stained cytoplasm and brightly stained nuclei. The optimum staining concentrations were very low (0.01% to 0.03%) and nontoxic. Using onion scale epidermis in which some cells had been killed by heating as a test system, and the plasmolysisdeplasmolysis rection as the ultimate test for cell vitality, results from CFW staining correctly predicted cell vitality for about 98% of the cells tested. This success rate was comparable to those for Evans blue, uranin or neutral red in this test system.